摘要:

AbstractThe pyrolysis of 2‐dimethylaminoethyl chloride in the temperature range of 360–400°C and the pressure range of 60–271 mmHg is a homogeneous, unimolecular, first‐order reaction giving dimethylvinyl amine and hydrogen chloride. 2‐Methoxyethyl chloride pyrolysis in the temperature range of 450–490°C and the pressure range of 53–110 mmHg by a similar unimolecular, first‐order reaction yields methylvinyl ether and hydrogen chloride. These reactions were carried out in a seasoned reaction vessel and in the presence of a propene inhibitor. The methylvinyl ether decomposes slowly into other products at the temperature of pyrolysis. The rate constants are given by the Arrhenius equations(a) 2‐dimethylaminoethyl chloride:\documentclass{article}\pagestyle{empty}\begin{document}$$ \log k(\sec ^{ - 1}) = (13.22 \pm 0.17) - (203.7 \pm 2.1)kJ/mol/2.303RT $$\end{document}(b) 2‐methoxyethyl chloride:\documentclass{article}\pagestyle{empty}\begin{document}$$ \log k(\sec ^{ - 1}) = (14.06 \pm 0.53) - (244.7 \pm 7.1)kJ/mol/2.303RT $$\end{document}The effects of polar β substituents in the 2 position of ethyl chloride are discussed in terms of anchimeric assistance and electron‐withdrawing deactivation in these elimination reactions. The present results are consistent with the heterolytic nature of the four‐centered cyclic transition state for the gas‐phas

ISSN:0538-8066    

DOI:10.1002/kin.550110202

出版商:John Wiley&Sons, Inc.    

年代:1979

数据来源: WILEY

摘要:

AbstractThe competitive photochlorination and chlorine photosensitized dehydrochlorination of 1,1,1,2‐C2H2Cl4have been studied over the temperature range of 349.4–404.5 K after less than 1% conversion. The results are discussed and a value of\documentclass{article}\pagestyle{empty}\begin{document}$$ \log k_{4A} (\sec ^{ - 1}) = (11.6\pm 0.6) - (16,400\pm 1000)/4.58T $$\end{document}is proposed for the reaction\documentclass{article}\pagestyle{empty}\begin{document}$$ {\rm CCl}_{\rm 3} {\rm CHCl}\mathop \to \limits^{(4{\rm A)}} {\rm CCl}_{\rm 2} {\rm CHCl + Cl} $$\end{document}This result, combined with existing thermochemical data, indicates that there is no evidence of an activation energy for the addition of a Cl atom on the most chlorinated carbon in trichloroethylene: in that case the selectivity of the addition of Cl on the less chlorinated carbon should not depend on temperat

ISSN:0538-8066    

DOI:10.1002/kin.550110203

出版商:John Wiley&Sons, Inc.    

年代:1979

数据来源: WILEY

摘要:

AbstractLifetime data have been obtained for the decay of SO2(3B10,0,0) at 25°C over the pressure range of 1–762 torr. The3B1state was populated by direct absorption to eliminate any possible complications in interpretation due to the participation of excited‐singlet manifolds. At pressures greater than about 10 torr, the measured lifetimes are longer than predicted from low‐pressure Stern–Volmer parameters. This deviation can be interpreted in terms of Freed's theory on collisionally induced intersystem crossing and provides unequivocal evidence to support earlier speculations that the lengthening of the lifetimes at high pressures is due to saturation in depopulation of the

ISSN:0538-8066    

DOI:10.1002/kin.550110204

出版商:John Wiley&Sons, Inc.    

年代:1979

数据来源: WILEY

摘要:

AbstractThe reaction\documentclass{article}\pagestyle{empty}\begin{document}$ CH\left({CH_3 } \right)\left({COOH} \right)_2 + I_2 \rightleftharpoons CI(CH_3)\left({COOH} \right)_2 + H^ + + I^ - $\end{document}was followed spectrophotometrically at 353 nm and 470 nm at 25°C under various conditions of pH and methylmalonic acid concentration. The equilibrium constant for the reaction is 0.11 ± 0.02. An iterative technique was used to integrate postulated rate equations. Agreement between experimental and calculated absorbance versus time curves was generally better than 0.005 A (approximately 5% of maximum) at both wavelengths for a mechanism where the rate‐determining step is formation of an enolate (k= 1.63 Θ 10−4± 0.03 Θ 10−4sec−1). The enolate may be rapidly transformed to the enol or enol carboxylate anion depending on the pH. All three forms are rapidly iodinated. The mechanism of general base catalysis is supported by rate increases proportional to base concentration in buffer solutions. The bases, acetate ion, chloracetate ion, sulfate ion, dichloracetate ion, and water, follow a Brønsted relationship

ISSN:0538-8066    

DOI:10.1002/kin.550110205

出版商:John Wiley&Sons, Inc.    

年代:1979

数据来源: WILEY

摘要:

AbstractThe bimolecular rate constant for the direct reaction of chlorine atoms with methane was measured at 25°C by using the very‐low‐pressure‐pyrolysis technique. The rate constant was found to be\documentclass{article}\pagestyle{empty}\begin{document}$$ k_1^{298} = (0.93 \pm 0.05) \times 10^{ - 13} cm^3 /mole \cdot \sec $$\end{document}In addition, the ratiok1/k−1was observed with about 25% accuracy:K1(298)= 1.3 ± 0.3. This gives a heat of formation of the methyl radical ΔH°f 298(CH3) = 35.1 ± 0.15 kcal/mol. A bond dissociation energy BDE (CH3 H) = 105.1 ± 0.15 kcal/mol in good agreement with literature valu

ISSN:0538-8066    

DOI:10.1002/kin.550110206

出版商:John Wiley&Sons, Inc.    

年代:1979

数据来源: WILEY

摘要:

AbstractOur previous mechanistic model for the Belousov–Zhabotinsky reaction has been revised to include a more realistic set of reactions for the oxidation pathways of the organic intermediates. A few other rate constants have also been modified to include new information. The revised mechanism reproduces the essential experimental observations, although the periods of oscillation are somewhat too long and oscillations cease at malonic acid concentrations about ten times greater than the observed lower limit. However, the essential features of the mechanism are clearly understoo

ISSN:0538-8066    

DOI:10.1002/kin.550110207

出版商:John Wiley&Sons, Inc.    

年代:1979

数据来源: WILEY

摘要:

AbstractThe kinetics of oxidation of glycine, alanine, phenylalanine, serine threonine, aspartic, and glutamic acid by acid permanganate were investigated to elucidate the mechanism of the reactions. The rate law was found to be\documentclass{article}\pagestyle{empty}\begin{document}$$ \frac{{ - d[Mn\left({VII} \right)]}}{{dt}} = k_0 [a\min oacid][Mn\left({VII} \right)] $$\end{document}The reactions were found to be acid catalyzed, and the kinetic data indicate the participation of the water molecules in the rate‐determining step as a proton‐abstracting agent from the substrate, as per Bunnett's hypothesis. As Ag+was found to catalyze these reactions, the oxidation of glycine and glutamic acid was studied, and the rate law was found to be\documentclass{article}\pagestyle{empty}\begin{document}$$ \frac{{ - d\ln [Mn\left({VII} \right)]}}{{dt}} = \frac{{Kk_c^{''} [a\min oacid][Ag^ +]}}{{1 + K[a\min oacid] = K[Ag^ +]}}$$\end{document}A probable mechanism consistent with the observed results is discus

ISSN:0538-8066    

DOI:10.1002/kin.550110208

出版商:John Wiley&Sons, Inc.    

年代:1979

数据来源: WILEY

摘要:

AbstractRelaxation rates for O2(1Σg+) by nonradiative pathways have been determined using the fast‐flow technique. O2(1Σg+) is formed from O2(1Δg) by an energy pooling process. O2(1Δg) is generated by passing purified oxygen through a microwave discharge. Oxygen atoms are removed by distilling mercury vapor through the discharge zone. It has been observed that the wall loss rate for O2(1Σg+) decreases with increasing pressure of oxygen and thus appears to be diffusion controlled. Quenching rate constants for O2, N2, and He have been determined and found to be (1.5 ± 0.1) × 104, (1.0 ± 0.05) × 106and (1.2 ± 0.1) × 105l./mol·sec,

ISSN:0538-8066    

DOI:10.1002/kin.550110209

出版商:John Wiley&Sons, Inc.    

年代:1979

数据来源: WILEY

摘要:

AbstractThe flash photolysis resonance fluorescence technique has been utilized to determine the rate constants for three reactions involving the hydroxyl radical [OH(2≅)] and three halogenated C2alkanes. The nominal temperature range covered was 250–375 K. The compounds studied and the resulting Arrhenius expressions in units of cm3/molec·sec areThe error limits in these expressions are such that they include any possible systematic errors due to the presence of impurities in the halocarbon samples. Tropospheric lifetimes have been calculated for the above species by combining the above rate constant data with global seasonally and diurnally averaged hydroxyl radical concentrat

ISSN:0538-8066    

DOI:10.1002/kin.550110210

出版商:John Wiley&Sons, Inc.    

年代:1979

数据来源: WILEY

摘要:

AbstractThe thermal decomposition of azomethane in the presence of propene has been investigated in the range of 568–638°K at reactant partial pressures of up to about 7 torr in the presence of at least 170 torr of argon. The elementary reactions taking place in such conditions are discussed in detail. It is shown that a situation approaching equilibrium is attained between the processesValues are obtained for the equilibrium constantK2, which can be described by the equation\documentclass{article}\pagestyle{empty}\begin{document}$$ {\rm logK}_{\rm 2} \left({{\rm atm}} \right){\rm = 7}{\rm .66 - 26}{\rm .1kcal/mol/(2}{\rm .3RT)} $$\end{document}Using the best available thermodynamic parameters for methyl and propene, it is concluded that those fors−butyl are in need of adjustment. We recommend the values ΔHf0(300°K) = 13.8 ± 1.0 kcal/mol andS3000(1 atm standard state) = 75.6 ± 3.0 cal/mol°K together with group additivity values of the heat capacity. A comparison of measured values ofK2with values calculated from independent measurements ofk2andk−2shows a discrepancy of about a fa

ISSN:0538-8066    

DOI:10.1002/kin.550110211

出版商:John Wiley&Sons, Inc.    

年代:1979

数据来源: WILEY